MT9VDDF3272G Datasheet, PDF (24/34 Pages) Micron Technology – DDR SDRAM REGISTERED DIMM

Initialization
To ensure device operation the DRAM must be ini-
tialized as described below:
1. Simultaneously apply power to VDD and VDDQ.
2. Apply VREF and then VTT power.
3. Assert and hold CKE at a LVCMOS logic low.
4. Provide stable CLOCK signals.
5. Wait at least 200µs.
6. Bring CKE high and provide at least one NOP or
DESELECT command. At this point the CKE input
changes from a LVCMOS input to a SSTL2 input
only and will remain a SSTL_2 input unless a
power cycle occurs.
7. Perform a PRECHARGE ALL command.
8. Wait at least ^tRP time, during this time NOPs or
DESELECT commands must be given.
9. Using the LMR command program the Extended
Mode Register (E0 = 0 to enable the DLL and E1 =
0 for normal drive or E1 = 1 for reduced drive, E2
through En must be set to 0; where n = most sig-
nificant bit).
10. Wait at least ^tMRD time, only NOPs or DESELECT
commands are allowed.
11. Using the LMR command program the Mode Reg-
ister to set operating parameters and to reset the
DLL. Note at least 200 clock cycles are required
between a DLL reset and any READ command.
12. Wait at least ^tMRD time, only NOPs or DESELECT
commands are allowed.
13. Issue a PRECHARGE ALL command.
14. Wait at least ^tRP time, only NOPs or DESELECT
commands are allowed.
15. Issue an AUTO REFRESH command (Note this
may be moved prior to step 13).
16. Wait at least ^tRFC time, only NOPs or DESELECT
commands are allowed.
17. Issue an AUTO REFRESH command (Note this
may be moved prior to step 13).
18. Wait at least ^tRFC time, only NOPs or DESELECT
commands are allowed.
19. Although not required by the Micron device,
JEDEC requires a LMR command to clear the DLL
bit (set M8 = 0). If a LMR command is issued the
same operating parameters should be utilized as
in step 11.
20. Wait at least ^tMRD time, only NOPs or DESELECT
commands are allowed.
21. At this point the DRAM is ready for any valid com-
mand. Note 200 clock cycles are required between
step 11 (DLL Reset) and any READ command.
256MB, 512MB (x72, ECC, SR)
184-PIN DDR SDRAM RDIMM
Figure 12: Initialization Flow Diagram
Step
1
VDD and VDDQ Ramp
2
Apply VREF and VTT
3
CKE must be LVCMOS Low
4
Apply stable CLOCKs
5
Wait at least 200us
6
Bring CKE High with a NOP command
7
PRECHARGE ALL
8
Assert NOP or DESELECT for ^tRP time
9
Configure Extended Mode Register
10
Assert NOP or DESELECT for ^tMRD time
11
Configure Load Mode Register and reset DLL
12
Assert NOP or DESELECT for ^tMRD time
13
PRECHARGE ALL
14
Assert NOP or DESELECT for ^tRP time
15
Issue AUTO REFRESH command
16
Assert NOP or DESELECT commands for ^tRFC
17
Issue AUTO REFRESH command
18
Assert NOP or DESELECT for ^tRFC time
19
Optional LMR command to clear DLL bit
20
Assert NOP or DESELECT for ^tMRD time
21
DRAM is ready for any valid command
pdf: 09005aef80e119b2, source: 09005aef807d56a1
DDF9C32_64x72G.fm - Rev. B 9/04 EN
24
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